In summary, a reflective optical beam smoke detector system has a detector unit, which includes both a transmitter and a receiver, and a retro-reflector. The detector unit and the reflector are placed opposite each other at opposing ends of a volume to be protected and monitored. The transmitter projects a beam, in this example an Infrared (IR) beam, on to the retro-reflector which reflects the IR beam along the same axis back to the receiver. Smoke in the beam path will reduce the amount of light returning to the receiver. The receiver continuously monitors the amount of light received and, if it drops below a certain user-defined threshold, then an alarm is initiated.
In normal circumstances (i.e. when no smoke is present), correct operation of the system relies upon stability of the amount of light being returned from the retro-reflector, as the receiver struggles to distinguish between a reduction in the level of light caused by the presence of smoke, and that caused by other factors, for example typical environmental movement of a building which can affect alignment of the system. The best (and only) way to improve stability is to correctly align the light beam on to the retro-reflector during initial installation.
Manual alignment can be a slow and drawn-out process, and it is surprisingly easy, even for professionals using this method, to achieve the wrong alignment—for instance, alignment with a reflective object which is not the reflector per se. Laser targeting—illumination of the reflector with a visible laser—has led to a reduction in wrong alignment; however, alignment of the laser on the reflector is no guarantee of alignment of the transmitter and the reflector, and the reflector and the receiver.
As such, there is a need for a more efficient and effective alignment procedure. Further, there is a need for an automated alignment procedure. The present invention is aimed at providing such improved procedures.